Mix It Right!

Figure 1. SSL’s X-ISM metering measures inter-sample distortion, and is available as a free download from www.solidstatelogic.com.

Check out the latest advances for mixing with DAWs

The best mics, recording techniques, and players
don’t guarantee great final results unless they’re
accompanied by a great mix—yet the face of mixing
has changed dramatically with the introduction
of the DAW, both for better and worse. Better,
because you don’t need to spend $250,000 for a
huge mixer with console automation, but worse
because we’ve sacrificed hands-on control and
transparent workflow for in-the-box cost-effectiveness
and convenience.

Or have we? Today’s DAWs have multiple
options—from track icons to color-coding to
configurable mixers—that help overcome the
limitations of displaying tons of tracks on a
computer monitor. While this can’t replace the
one-function/one-control design of analog gear,
some tasks (such as grouping and automation)
are now actually easier to do than they were
back in the day.

As to hands-on control, controller-related products
keep expanding and offering more possibilities,
from standard control surfaces with
motorized faders, to FireWire or USB mixers, to
keyboard workstations (such as Yamaha’s
Motif XS/XF series or Korg’s M3) pressed into
service as controllers. These all help re-create
“the analog experience.”

Unlike most of our roundups, this time we’re
not reviewing gear but instead looking at
techniques and features—then correlating how
those are implemented in various DAWs.

And speaking of DAWs, if you’ve held off on
upgrading your DAW of choice, now might be
the time to reconsider. As DAW feature sets mature, more companies focus their efforts on
workflow and efficiency. While these kinds of
updates may not seem compelling when looking
over specs on a website, in practice, they can
make the recording and mixing process more
enjoyable and streamlined. And isn’t that what
we all want in the studio?

GAIN-STAGING
The typical mixer has several places where you
can set levels; proper gain-staging makes sure
that levels are set properly to avoid either distortion
(levels too high) or excessive noise (levels
too low).

There’s some confusion about gain-staging,
because it works differently in hardware and software.
With hardware, you’re always dealing with a
fixed, physical amount of headroom and dynamic
range, which must be respected. Modern virtual
mixers (with 32-bit floating-point resolution and
above) have almost unlimited dynamic range in
the mixer channels themselves—you can go “into
the red” yet never hear distortion. However, at
some point, the virtual world meets the physical
world, and is subject to hardware limitations.

When you gain-stage, work backward from the
output; make sure that the output level doesn’t
overload the physical audio interface. I also treat
–6 to –10dB output peaks as “0.” Leave some
headroom to allow for inter-sample distortion (Figure
1; see the Roundup in the June 2010 issue
for more information); also, it seems converters like to have a little “breathing room.” Remember,
these levels can—and usually will—be brought up
during the mastering process anyway. Then, set individual
channel levels so that the mixed output’s
peaks don’t exceed that –6 to –10dB range.

CONFIGURABLE MIXERS
One of the most useful features of virtual mixers is
that you can configure them to show only what’s
needed for the task at hand, thus reducing screen
clutter (Figure 2).

Mixing often happens in stages: First, you
adjust levels; then EQ, then stereo placement, aux
busing, etc. Granted, you’ll go back and forth as
you tweak things—for example, changing EQ might
affect levels—but if you save particular mixer configurations,
you can recall them as needed. Here
are some examples of ways to use this feature
when mixing.

Figure 3. Acoustica’s Mixcraft 5 is one of several programs that offer track icons to make quick, visual identification of DAW tracks.

· The meter bridge. This is more applicable to
tracking than mixing, but is definitely worth a
mention. If you hide everything except meters
(and narrow the mixer channel strips, if possible),
then you essentially have a meter bridge. Because
software mixers often do not adjust incoming
levels from an interface when recording (typically, the interface provides an applet for that task), you
can leave the “meter bridge” up on the screen to
monitor incoming levels along with previously recorded
tracks.
· Hiding non-essentials. Visual distractions work
against mixing; some people even turn off their
monitors, using only a control surface, so they can
concentrate on listening. While you might not
want to go to that extreme, when mixing you
probably don’t need to see I/O setups, and once
the EQ settings are nailed, you probably won’t
need those either. You may want to adjust aux bus
sends during the course of a mix, but that task
can be relegated to automation, letting you hide
buses as well.
· Channel arrangement. With giant hardware
mixers, it was common to re-patch tape channel
outs to logical groupings on the mixer, so that all
the drum faders would be adjacent to each other;
ditto vocals, guitars, etc. With virtual mixers, you
can usually do this just by dragging the channels
around: Take that final percussion overdub you
added on track 26, and move it next to the drums.
Move the harmony vocals so they’re sitting next to
the lead vocal, and re-arrange the rhythm tracks
so they flow logically. And while you’re at it, think
about having a more or less standardized
arrangement in the future—for example, starting off
with drums on the lowest-numbered tracks, then
bass, then rhythm guitars and keyboards, and
finally moving on to lead parts and “ear candy”
overdubs. The less you need to think about where
to find what you want, the better.
· Color-coding. Color-coding tracks can be
tremendously helpful if done consistently. I go by
the spectrum mnemonic: Roy G. Biv (red, orange,
yellow, green, blue, indigo, violet). Drums are red,
bass is orange, melodic rhythm parts are yellow,
vocals are green, leads are blue, percussion is
indigo, and effects are violet. When you have a lot
of tracks, color-coding makes it easy to scroll to
the correct section of the mixer (if scrolling is
necessary, which I try to avoid if possible).
· Track icons. When I first saw these on Garage
Band, I thought the concept was silly—who needs
cute little pictures of guitars, drums, etc.? But I
loaded track icons once when I wanted to make
an article screenshot look more interesting, and
have been using them ever since. The minute or
two it takes to locate and load the icons pays off
in terms of parsing tracks rapidly (Figure 3).
Coupled with color-coding, you can jump to a
track visually without having to read the
channel name.

CHANNEL STRIPS
Several DAWs include channel strips with EQ and
dynamics control (Figure 4), or even more
esoteric strips (e.g., a channel strip dedicated to
drums or vocals), but third-party channel strips are
also available—see Figure 5. If there are
certain settings you return to frequently (I’ve found
particular settings that work well with my voice for
narration, so I have a narration channel strip preset),
these can save time compared to inserting individual
plug-ins. Although I often make minor tweaks, it’s
easier than starting from scratch.

Even if you don’t have specific channel strips,
many DAWs let you create track presets that include
particular plug-in configurations. For example, I made a “virtual guitar rack” track preset designed
specifically for processing guitar with an amp sim,
compression, EQ, and spring reverb.

BUSING
There are three places to insert effects in a typical
mixer:
· Channel inserts, where the effect processes only
that channel
· Master inserts, where the processor affects the
entire mix (e.g., overall limiting or EQ)
· Buses, where the processor affects anything
feeding that bus

Proper busing can simplify the mixing process (Figure
6), and make for a happier CPU. In the
days of hardware, busing was needed because
unlike plug-ins, which you can instantiate until your
CPU screams “no more,” a hardware processor
could process only one signal path at a time. Therefore,
to process multiple signals, you had to create a
signal path that could mix together multiple signals—
in other words, a bus that fed the processor.

The most common effects bus application is
reverb, for two reasons. First, high-quality reverbs
(particularly convolution types) generally use a lot of
CPU power, so you don’t want to open up multiple
instances. Second, there’s an aesthetic issue: If
you’re using reverb to give a feeling of music being
in an acoustic space, it makes sense to create a
single, common acoustic space. Increasing a channel’s
reverb send places the sound more in the
“back,” and less send places it more in the “front.”

A variation on this theme is to have two reverb
buses and two reverbs—one for sustained instruments,
and one for percussive instruments. Use two
instances of the same reverb, with very similar settings
except for diffusion. This is because you generally
want lots of diffusion with percussive sounds to avoid
hearing discrete echoes, and less diffusion with
sustained instruments (like vocals or lead guitar)
so that the reverb isn’t too “thick,” thus muddying the
sustained sound. You’ll still have the feeling of a unified
acoustic space, but with the advantage of being able
to decide how you want to process individual tracks.

Of course, effects buses aren’t only good for
reverb. I sometimes put an effect with very light distortion
in a bus, and feed in signals that need some
“crunch”—for example, adding a little grit to kick and
bass can help them stand out more when playing
the mix through speakers that lack bass response.
Tempo-synced delay for dance music cuts also
lends itself to busing, as you may want a similar
rhythmic delay feel for multiple tracks.

GROUPING
Grouping (Figure 7) is a way to let one fader control
many faders, and there are two main ways of doing
this. The classic example of old-school grouping is a
drum set with multiple mics; once you nail the relative
balance of the individual channels, you can send
them to a bus, which allows raising and lowering the
level of all mics with a single control. With this
method, the individual fader levels don’t change.

Figure 6. Logic Pro’s “Inspector” for individual channels shows the channel’s level on the left; on the right, you’ll see parameters for whichever send that you select (or the output bus).

The other option is not to use a bus, but
assign all the faders to a group. In this case, moving
one fader causes all of the other faders to
follow. Furthermore, with virtual mixers, it’s often
possible to choose whether group fader levels
move linearly or ratiometrically. With a linear
change, moving one fader a certain number of dB
raises or lowers all faders by the same number of
dB. When using ratiometric changes, raising or
lowering a fader’s level by a certain percentage
raises or lowers all grouped fader levels by the
same percentage, not by a specific number of
dB. In almost all cases, you’ll want to choose a
ratiometric response.

Another use for grouping is to fight “level creep,”
where you raise the level of one track, then another,
and then another, until you find the master is creeping
up to zero or even exceeding it—see the section
on Gain-Staging. Temporarily group all of the faders
ratiometrically, then bring them down (or up, if your
level creep went in the opposite direction) until the
output level is in the right range.

CONTROL SURFACES
Yes, I know people mix with a mouse. But I highly
recommend using a control surface, not because I
was raised with hardware mixers, but because a
control surface is a “parallel interface”—you can
control multiple aspects of your mix simultaneously—
whereas a mouse is more like a serial interface,
where you can control only one aspect of a mix
at a time.

Furthermore, I prefer a mix to be a performance.
You can add a lot more life to a mix by using faders
not just to set static levels, but to add dynamic and
rhythmic variations (i.e., moving faders subtly in time
with the music) that impart life and motion to the mix.

There are many control surface options (Figure 8). One is to use a control
surface, dedicated to mixing functions, that produces control signals that your DAW
can interpret and understand. Typical models include the Avid Artist Series (formerly
from Euphonix), Mackie Control, Cakewalk VS-700C, Behringer BCF2000, Alesis
Master Control, etc. The more advanced models use motorized faders, which simplify
the mixing process because you can overdub automation moves just by grabbing
faders and punching in. If that option is too expensive, there are less-costly
alternatives, such as the Frontier Design AlphaTrack, PreSonus Faderport, Cakewalk
VS-20 for guitarists, and the like. These generally have fewer faders and options,
but are still more tactile than using a mouse.

Figure 7. In Presonus Studio One Pro, the top three tracks have been selected and are about to be grouped, so edits applied to one track apply to the other grouped tracks.

There’s yet another option that might work even better for you: an analog or digital
mixer. I first got turned on to this back in the early days of DAWs, when I had a Panasonic
DA7 digital mixer. It had great EQ and dynamics that often sounded better than
what was built into DAWs, and had motorized faders and decent hardware busing
options. It also had two ADAT cards so I could run 16 digital audio channels into the
mixer, and I used the Creamware SCOPE interface with two ADAT outs. I could
assign tracks to the SCOPE ADAT outs, feed these into the DA7, and mix using the
DA7. Syncing the motorized fader “moves” to the DAW allowed for automated mixes.

This had several advantages, starting with hands-on control. Also, by using the
DA7’s internal effects, I not only had better sound quality but also lightened the computer’s
CPU load. And it was easier to interface hardware processors with the DA7
compared to interfacing them with a DAW (although most current DAWs make it easy
to treat outboard hardware gear like plug-ins if your audio interface can dedicate I/O to
the processors). Finally, the DA7 had a MIDI control layer, so it was even possible to
control MIDI parameters in virtual instruments and effects plug-ins from the same control
surface that was doing the mixing. While the DA7 is long gone, Yamaha offers the
02R96VCM and 02R96VCM digital mixers, which offer the same general advantages.

However, that’s just one way to deal with deploying a control surface. You can use a
high-quality analog mixer, or something like the Dangerous Music 2-BUS and D-BOX.
Analog mixing has a somewhat different sonic character compared to digital mixing,
although I wouldn’t go so far as to say one is inherently better than the other. (It’s more
like a Strat vs. Les Paul situation—different strokes for different folks.) The main issue
will be I/O limitation, because you have to get the audio out of the DAW and into the
mixer. If you have 43 tracks and your interface has only eight discrete outs—trouble. The workaround is to create stems by assigning related tracks (e.g., drums, background
vocals, rhythm guitars, etc.) to buses, then sending the bus outputs to the interface. In
some ways this is a fun way to mix, as you have a more limited set of controls and it’s
harder to get “lost in the tracks.”

Today’s FireWire and USB 2.0 mixers (M-Audio, Alesis, Phonic, Mackie, etc.) can
provide a best-of-both-worlds option. These are basically traditional mixers that can
also act as DAW interfaces—and while recording, they have enough inputs to record a
multi-miked drum set and several other instruments simultaneously. Similarly, when it’s
time to mix, you might have enough channels to mix each channel individually, or at
least mix a combination of individual channels and stems. Mackie’s Onyx “i” series is
even Pro Tools M-Powered compatible.

SCREEN SETS
Different programs call this concept by different names, but basically, screen sets are about
being able to call up a particular configuration of windows with a simple keyboard shortcut
or menu item (Figure 9) so you can switch instantly among various views.

Like many of today’s DAW features (track icons, color-coding, configuring mixers,
and the like), it requires some time and thought to create a useful collection of screen
sets, so some people don’t bother. But this initial time investment is well worth it,
because you’ll save far more time in the future. Think about how often you’ve needed
to leave a mixer view to do a quick edit in the track or arrange view: You resize, move
windows, change window sizes, make your changes, then resize and move all over
again to get back to where you were. It’s so much simpler to have a keyboard shortcut
that says, “hide the mixer, pull up the arranger view, and have the piano-roll editing
window ready to go,” and after doing your edits, having another shortcut that says,
“hide all that other stuff and just give me the mixer.”

DIGITAL METERING LIMITATIONS
You can’t always trust digital metering: For example, to indicate clipping, digital meters
sometimes require that several consecutive samples clip. Therefore, if only a few samples
clip at a time, your meters may not indicate that clipping has occurred. Also, not
all digital gear is totally consistent—especially hardware. In theory, a full-strength digital
signal in which all the bits are “1” should always read 0dB; however, some designers
provide a little headroom before clipping actually occurs—a signal that causes a digital
mixer to hit –1dB might show as 0dB on your DAW.

Figure 9. Logic’s Screensets get their own menu for quick recall and switching among views.

It’s a good idea to use a test tone to check out metering characteristics of all your
digital gear. Here are the steps:

1 Set a sine wave test tone oscillator to about 1kHz, or play a synthesizer sine wave
two octaves above middle C (a little bit above 1kHz).2 Send this signal into an analog-to-digital converter.3 Patch the A/D converter’s digital out to the digital in of the device you want
to measure.4 Adjust the oscillator signal level until the indicator for the device being tested just
hits –6dB. Be careful not to change the oscillator signal level!5 Repeat step 3 for any other digital audio devices that you want to test.

In theory, all your other gear should indicate –6dB, but if not, note variations in your
studio notebook for future reference.

WHY YOU NEED A
DUAL-MONITOR SETUP

If you’re not using two (or even three) monitors, you’ll kick yourself
when you finally get an additional monitor and realize just
how much easier DAW-based mixing can be. Dedicate the second
monitor to the mixer window, and the main monitor to showing
tracks, virtual instrument GUIs, etc.—or stretch the mixer over
both monitors to emulate old-school hardware-style mixing.

Your graphics card will need to handle multiple monitors
(although some computers have that capability “out of the
box”). I use Matrox cards; they’ve never let me down. However,
combining different monitor technologies can be problematic—
for example, you might want to use an old 19" CRT monitor
along with a new LCD monitor, only to find that the refresh
rates have to be set to the lowest common frequency. If the
LCD wants 60Hz, then you’re stuck with 60Hz (i.e., flicker
city!) on the CRT. If possible, use matched monitors, or at
least matching technology.

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